@Misc{NIST_ASD,
author = {A.~Kramida and {Yu.~Ralchenko} and
J.~Reader and {and NIST ASD Team}},
HOWPUBLISHED = {{NIST Atomic Spectra Database
(ver. 5.8), [Online]. Available:
{\tt{https://physics.nist.gov/asd}} [2021, April 22].
National Institute of Standards and Technology,
Gaithersburg, MD.}},
year = {2020},
}